Most electronic devices today incorporate one or more printed wiring boards into their design. These printed wiring boards have become very sophisticated, having multilevels with each level employing connections on each side thereof. The electronic devices, such as computers, are themselves becoming more and more complex and sophisticated.
As the sophistication increases, so does the need for power and power distribution systems. It is now necessary to transport power levels in the order of 100 amps or more between different layers of the multilayer printed wiring board.
In a typical situation, a power device is plugged into a top layer of the circuit board, and current from the device must be delivered to a mid-level layer, or plane. Thus, the current must flow from the top layer, through all intermediate layers, to the desired layer.
In the prior art, this distribution of power between layers has been accomplished using power vias, or current conducting channels, fashioned in the printed wiring board. The vias would be insulated from each layer as it passed through that layer and would be connected electrically only to the layer to, or from, which the power transfer was to occur. In some arrangements, a metal socket would extend from the surface to the desired power plane for the purpose of conducting power from the power device, commonly called a power brick.
The amperage capacity of a power brick having the dimensions of 21/2 by 41/2 inches has increased from 30 amps to over 100 amps and the vias of the prior art are not capable of transferring that much power due, in part, to the fact that the resistance of the vias caused heat build up resulting in both component and board failures, as well as fire hazards.
Therefore, one object of the present invention is to decrease electrical resistance by increasing the surface contact of the metallized surfaces in order to transfer more current.
Another object of the present invention is to provide low impedance and low inductance to the circuit.
A further object of the present invention is to enable a cost-effective and reliable multiplane printed circuit board connection to high amperage electric power devices.
A still further object is to accomplish the desired result using existing printing wiring board construction techniques.